This invention relates generally to the analysis of both supersonic and subsonic flowing gases, and in particular it relates to the analysis of flow fields in supersonic gas lasers such as hydrogen fluoride (HF) or deuterium fluoride (DF) chemical lasers.
Chemical lasers are efficient lasers, having great average power capabilities and other advantageous characteristics such as the ability to produce laser power from a reaction of gases that are easily bottled. These advantages have made the chemical laser the subject of much study and investigation, but these efforts have been hampered by a lack of any precise method for analyzing the mixing reacting flow fields in such lasers. The efficiency of chemical lasers is controlled in large part by the mixing of the reactant gases. Accurate, visual mappings of the flow fields are critically needed to form a data base for theoretical modeling and to improve mixing efficiencies.
The typical diagnostic approach used in the past to analyze laser flow fields has been to observe the visual chemiluminescence of HF or DF overtone emission. This approach suffers from the fact that the chemiluminescence is not well localized and spatial resolution is lost. For example, in order to observe the visible emission originating from the gases in the middle of a typical laser nozzle bank due to chemiluminescence, you must look through the emission from gases flowing between the viewer and the area being investigated. It is apparent that this would obscure observations and make interpretations more difficult and subject to error.